The objective of this work is to study the potential of hay as stabilizing agent for cohesive soils, which exhibit several engineering problems. For this propose three types of soils were selected from the eastern part of Irbid city in Jordan, soil-hay mixtures where prepared with O,2,4,6,and 10 percents by weight of the soil. Both natural and hay-treated soils were subjected to similar laboratory tests to evaluate the effect of hay on physical and engineering properties. The main tests were performed at the lab are compaction; Atterberg limits, unconfined compressive strength, California bearing ratio, consolidation and direct shear test, they prepared at 95 percent relative compaction. The experimental results indicate that compaction process decreases maximum dry density and increases optimum water content with the increase of the hay content. Both liquid and plastic limits were increases, while the increase in plastic limit is slightly small than liquid limit This Leeds to increase the plasticity index of the soil. The unconfined compressive strength increased up to certain limit of hay content after this percent the unconfined compressive strength decrease. The direct shear parameters were increased with the increase of hay percent, but the increase in the cohesion is limited at certain hay percent after this percent the cohesion decreased. The California Bearing Ratio for three soils were increased with the increase of hay content up to six percent, after that it will decrease. The swell percent increased with increasing of hay percent and the compression index increased with increasing of hay content for all soils.